The recent emergence of multiple variants of SARS-COV-2, the causative agent of COVID-19, has led to a frenzy of confusing media coverage that has left many with more questions than answers. What does it mean for the virus to mutate? Are these variants more infectious or deadly? Will the vaccines still protect from these variants? Should I be worried? While these questions are still actively being pursued by scientists and physicians around the world, an early image has begun to form.
The process of replicating genetic material is inherently error-prone. This is true for your skin cells as they divide to replace dying cells, for bacteria in your gut as they grow, and for viruses that replicate themselves by infecting a host. The SARS-COV-2 virus carries genetic material, called RNA, that serves as replication instructions – allowing it to make copies of itself once it infects a human cell. As the virus continues to replicate in an infected individual, the error-prone replication machinery occasionally makes a mistake while it copies the RNA instructions. The vast majority of these errors, called mutations, either do not affect the genetic instructions (“silent” mutations) or negatively affect the ability of the virus to replicate. However, these mutations can sometimes lead to changes in the RNA that encode for more efficient viral replication or an increased ability to bind to, and infect, human target cells. These different “versions” of the mutated virus are referred to as variants or strains. Given enough time and sufficient spread of any viral pathogen across a population, as is the case with the spread of SARS-COV-2 virus around the world, the emergence of variants is almost biologically guaranteed.
The three main SARS-COV-2 variants of concern are the B.1.1.7, the B.1.351, and the P1 variants, also know respectively as the United Kingdom, South Africa, and Brazil variants based on where they were first observed. All three of these variants have been observed to have higher transmissibility – meaning they can be passed on from one infected person to another more easily. The UK variant, in particular, is up to 50% more contagious than the original unmutated (or parental) SARS-COV-2 strain. Preliminary data also suggests that while it does not increase the severity of disease (patients infected with the UK variant are not sicker compared to those infected with the parental variant), it is linked to an increased risk of death.
Some preliminary studies have suggested that the mutations these variants carry make them less likely to be detected by pre-existing antibody immunity from patients who have previously been infected by the virus. However, the immune response to SARS-COV-2 is complex and multi-faceted. This enables other immune cells to compensate, and preliminary data suggests that cell-mediated immunity to the variants remains strong.
These mutations, however, raise concerns about continued vaccine efficacy. Indeed, some early indications suggest that the efficacy of the J&J vaccine could potentially be lower against the South African strain. Pfizer has also reported slightly lower efficacy in protecting against this strain. Given the recent emergence of these variants, more time and data are needed to paint a more complete picture. Yet, even if these concerns are verified, the approved SARS-COV-2 vaccines provide very potent antibody and cellular immune responses. Vaccination remains your best bet for pre-emptively fighting off the virus – particularly when compared to the alternative: no vaccine at all!
This is a rapidly evolving situation receiving a lot of attention from researchers around the world. While the early indications suggest the variants are indeed concerning, the route of transmission remains unchanged. Ultimately, the SARS-COV-2 variants are spread like any other respiratory virus. The best protection against the variants is the best protection against all respiratory viruses:
